In addition to the general sibling comments, I can personally attest that Shriram knows what the Y combinator is and has been teaching students about it for at least 25 years. My own lecture notes from one of his classes about the lambda calculus and the Y combinator were for a long time on the front page of google results for info about either!
For added fun, the day he teaches it in class, he wears a t-shirt from Y-combinator the startup accelerator (and explains what its name means).
Now that we've gotten that out of the way, it remains unclear what is surprising or unpleasantly surprising about the code.